The present invention relates to a water repellent silicone coating agent composition. Specifically, it relates to a water repellent silicone coating agent composition possessing superior flowability and coating properties and capable of forming cured films exhibiting excellent water repellent properties after coating.
Typically, water repellent silicone coating agents are used in a state in which their solid matter is diluted with an organic solvent, and, as a result of the evaporation of the organic solvent after coating, form cured coating films exhibiting water repellent properties. However, coating agents diluted with a large amount of organic solvent present problems in terms of environmental safety and hygiene, and in recent years they have been gradually phased out. On the other hand, if the amount of the organic solvent combined therewith is small, the viscosity of the coating agent increases, and as a result its flowability and coating properties decrease, which makes obtaining a uniform coating film more difficult. For these reasons, there is demand for silicone coating agents that are capable of forming cured films exhibiting excellent water repellent properties after coating and which possess superior flowability and coating properties even without using a large amount of organic solvent.
It is an object of the present invention to provide a water repellent silicone coating agent composition possessing superior flowability and coating properties and capable of forming cured films exhibiting excellent water repellent properties after coating.
The present invention is a water repellent silicone coating agent composition comprising
(A) 100 parts by weight of diorganopolysiloxane having a viscosity of 20 to 20,000 mPaxc2x7s at 25xc2x0 C. in which the terminal ends of the molecular chain are blocked by silanol groups or silicon-bonded hydrolyzable groups,
(B) 5 to 100 parts by weight of a cross-linking agent represented by general formula RaSiX4-a, in which R is a monovalent hydrocarbon group comprising 1 to 10 carbon atoms, X is a hydrolyzable group, and subscript a is an integer of 0 to 2,
(C) 0.1 to 20 parts by weight of a condensation reaction catalyst,
(D) 8 to 50 parts by weight of a hydrophobic surface treated dry process silica having a carbon content of 3.7 to 5% by weight and a bulk density of 40 to 99 g/L, or a hydrophobic surface treated dry process silica having a carbon content of 2.7 to 5% by weight and a bulk density of 100 to 300 g/L,
(E) 1 to 10 parts by weight of an organic functional silane coupling agent-based adhesion-imparting agent,
(F) an organic solvent having a boiling point of 100 to 200xc2x0 C. in an amount of 4 to 100 wt % based on the total of component (A) to component (E), and optionally
(G) 1 to 50 parts by weight of a non-reactive silicone fluid having a viscosity of 10 to 10,000 mPaxc2x7s at 25xc2x0 C.
The present invention is a water repellent silicone coating agent composition comprising
(A) 100 parts by weight of diorganopolysiloxane having a viscosity of 20 to 20,000 mPaxc2x7s at 25xc2x0 C. in which the terminal ends of the molecular chain are blocked by silanol groups or silicon-bonded hydrolyzable groups,
(B) 5 to 100 parts by weight of a cross-linking agent represented by general formula RaSiX4-a, in which R is a monovalent hydrocarbon group comprising 1 to 10 carbon atoms, X is a hydrolyzable group, and subscript a is an integer of 0 to 2,
(C) 0.1 to 20 parts by weight of a condensation reaction catalyst,
(D) 8 to 50 parts by weight of a hydrophobic surface treated dry process silica having a carbon content of 3.7 to 5% by weight and a bulk density of 40 to 99 g/L, or a hydrophobic surface treated dry process silica having a carbon content of 2.7 to 5% by weight and a bulk density of 100 to 300 g/L,
(E) 1 to 10 parts by weight of an organic functional silane coupling agent-based adhesion-imparting agent,
(F) an organic solvent having a boiling point of 100 to 200xc2x0 C. in an amount of 4 to 100 wt % based on the total of component (A) to component (E), and optionally
(G) 1 to 50 parts by weight of a non-reactive silicone fluid having a viscosity of 10 to 10,000 mPaxc2x7s at 25xc2x0 C.
Hereinbelow, the present invention is explained in detail. Component (A) is a diorganopolysiloxane having a viscosity of 20 to 20,000 mPaxc2x7s at 25xc2x0 C. in which the terminal ends of the molecular chain are blocked by silanol groups or silicon-bonded hydrolyzable groups and is the primary component of the present composition. Suggested hydrolyzable groups include dimethyl ketoxime, methyl ethyl ketoxime, and other diorganoketoxime groups; methoxy, ethoxy, and other alkoxy groups; acetoxy, and other acyloxy groups; N-butylamino and other organoamino groups; methylacetoamido and other organoacylamido groups; N,N-diethylhydroxyamino and other N,N-diorganohydroxyamino groups; and propenoxy, and other alkenyloxy groups. Among these, alkoxy groups are preferable. In addition, organic groups bonded to silicon atoms in the diorganopolysiloxane are exemplified by unsubstituted monovalent hydrocarbon groups such as methyl, ethyl, propyl, and other alkyl groups; vinyl, allyl, and other alkenyl groups; phenyl, and other aryl groups; and by 3,3,3-trifluoropropyl, nonafluorohexyl, and other halogen atom-substituted hydrocarbon groups. Dimethylpolysiloxane having both terminal ends of the molecular chain blocked by silanol groups or methoxy groups is preferable as the diorganopolysiloxane of component (A). The viscosity of component (A) is 20 to 20,000 mPaxc2x7s and preferably 40 to 15,000 mPaxc2x7s at 25xc2x0 C.
Component (B) is a cross-linking agent represented by general formula RaSi4-a in which R is a monovalent hydrocarbon group comprising 1 to 10 carbon atoms exemplified by methyl, ethyl, propyl, tert-butyl, 2-ethylhexyl, and other alkyl groups; vinyl, allyl, and other alkenyl groups; and phenyl and other aryl groups. Among these, alkyl groups and alkenyl groups are preferable and methyl is especially preferable. X is a hydrolyzable group exemplified by dimethyl ketoxime, methyl ethyl ketoxime, and other diorganoketoxime groups; methoxy, ethoxy, and other alkoxy groups; acetoxy, and other acyloxy groups; N-butylamino and other organoamino groups; methylacetoamido and other organoacylamido groups; N,N-diethylhydroxyamino and other N,N-diorganohydroxyamino groups; and propenoxy, and other alkenyloxy groups. The subscript a is an integer of 0 to 2. Suggested examples of component (B) include tetrakis(methylethylketoxime)silane, methyl tris(methylethylketoxime)silane, vinyl tris(methylethylketoxime)silane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltriacetoxysilane, tetramethoxysilane, tetraethoxysilane, methyltriisopropenoxysilane, tetraisopropenoxysilane, and methyl tri(N,N-diethylamino)silane. The amount of component (B) in the present composition is 5 to 100 parts by weight per 100 parts by weight of component (A), and from the standpoint of curability preferably in the range of from 8 to 40 parts by weight on the same basis.
The condensation reaction catalyst of component (C) can be a well-known prior-art silanol condensation catalyst including dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dimalate, dioctyltin dilaurate, dioctyltin dimalate, tin octylate, and other organotin compounds; isopropyltriisostearoyl titanate, isopropyltris(dioctylpyrophosphato)titanate, bis(dioctylpyrophosphato)oxyacetato titanate, tetraalkyl titanate, and other organotitanate compounds; tetrabutyl zirconate, tetrakis(acetylacetonato)zirconium, tetraisobutyl zirconate, butoxytris(acetylacetonato)zirconium, zirconium nathphenate, and other organozirconium compounds; tris(ethylacetoacetato)aluminum, tris(acetylacetonate)aluminum, and other organoaluminum compounds; zinc naphthenate, cobalt naphthenate, cobalt octylate, and other organometallic catalysts; diethanolamine, triethanolamine, and other amine-series catalysts that do not contain organosilicon compounds. The amount of component (C) is 0.1 to 20 parts by weight, and, from the standpoint of curability, preferably in the range of from 1 to 15 parts by weight per 100 parts by weight of component (A).
The hydrophobic surface treated dry process silica of component (D) is a reinforcing filler in the present composition. Component (D) is a hydrophobic surface treated dry process silica having a carbon content of 3.7 to 5% by weight and a bulk density of 40 to 99 g/L or a hydrophobic surface treated dry process silica with a carbon content of 2.7 to 5% by weight and a bulk density of 100 to 300 g/L. The use of hydrophobic surface treated dry process silica with such specific carbon content and bulk density makes it possible to obtain a coating agent of superior flowability, coating properties, and water repellent properties even without diluting it with a large amount of organic solvent. The carbon content mentioned in the present invention is a value determined using a CHN analyzer, and the bulk density is determined by filling a container of a predetermined volume with a hydrophobic surface treated dry process silica and weighing it. This type of hydrophobic surface treated dry process silica of component (D) is prepared, for example, by treating an untreated dry process silica with a BET specific surface area of 50 to 500 m2/g using hexamethyldisilazane, dimethyldichlorosilane, cyclic dimethylsiloxane, and other organosilicon compounds. A hydrophobic surface treated silica treated with hexamethyldisilazane is particularly preferable. A treatment process in which an excess amount of hexamethyldisilazane and water is used is suggested as a method for increasing the carbon content of the silica. In addition, processes in which compression is used or processes in which the silica is subjected to mechanical shear are suggested as methods for regulating the bulk density. In component (D), the hydrophobic surface treated dry process silica with a carbon content of 3.7 to 5% by weight and a bulk density of 40 to 99 g/L preferably has a carbon content within the range of from 3.8 to 4.5% by weight and bulk density within the range of from 50 to 95 g/L, and even more preferably has a carbon content that exceeds 4% and is not higher than 4.5% by weight. The other embodiment of component (D) which is a hydrophobic surface treated dry process silica with a carbon content of 2.7 to 5% and a bulk density of 100 to 300 g/L preferably has a carbon content in the range of from 2.8% to 4% and a bulk density of 100 to 200 g/L. The amount of component (D) is 8 to 50 parts by weight, and, from the standpoint of coating properties and water repellent properties, preferably in the range of from 9 parts by weight to 40 parts by weight per 100 parts by weight of component (A).
The organic functional silane coupling agent of component (E) is an adhesion-imparting agent specifically exemplified by xcex3-aminopropyltrimethoxysilane, xcex3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane and other aminosilanes; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and other epoxysilanes; as well as reaction products of the above-described aminosilanes and epoxysilanes. The amount of component (E) added to the present composition is 1 to 10 parts by weight, and preferably in the range of from 1.5 parts by weight to 8 parts by weight per 100 parts by weight of component (A).
The organic solvent of component (F) improves the coating properties of the present composition by adjusting its viscosity. Such an organic solvent should have a boiling point in the range of from 100xc2x0 C. to 200xc2x0 C. and be capable of dissolving component (A) and component (B), and is selected appropriately depending on the type and amount used. Specifically suggested organic solvents include toluene, xylene, naphthene (trade name: Naphthesol LL, from Nippon Petrochemicals Co., Ltd.), and other aromatic hydrocarbons; 2-pentanone, 4-methyl-2-pentanone, and other ketones; isoparaffin, normal paraffin (trade names: Isosol 200, 300, Normal Paraffin SL, from Nippon Petrochemicals Co., Ltd.), and other aliphatic hydrocarbons; butyl acetate, isobutyl acetate, and other esters; hexamethyldisiloxane, octamethyltrisiloxane, and other volatile silicones which may be used singly or as mixed solvents of two or more solvents. The amount of component (F) is from 4 wt % to 100 wt %, and preferably from 10 wt % to 50 wt % relative to the total of component (A) to component (E). This is due to the fact that when the amount is less than 4 wt%, the coating properties are poor and when it exceeds 100 wt % the coating film becomes too thin.
Although the present composition comprises the above-described component (A) to component (F), optionally a non-reactive silicone fluid with a viscosity of 10 mPaxc2x7s to 10,000 mPaxc2x7s may be added and combined therewith as component (G) in order to improve its water repellent properties. A representative example of such a silicone fluid is a polydiorganosiloxane that does not contain in its molecule condensation reactive groups, such as hydrolyzable groups and silanol groups. In addition to methyl, ethyl, propyl, and other alkyl groups; vinyl, allyl, and other alkenyl groups; phenyl, and other aryl groups, phenethyl, 2-phenylpropyl and other aralkyl groups, one may suggest polyether groups such as polyoxyethylene chains, polyoxypropylene chains, oxyethylene-oxypropylene chains as groups bonded to silicon atoms. It is recommended that aralkyl groups contained in the aforementioned groups constitute 2 to 40% of the total amount of silicon-bonded organic groups. Specific examples of component (G) include a fluid polydimethylsiloxane modified with polyoxyalkylene, a fluid copolymer of dimethylsiloxane, methyl(2-phenylpropyl)siloxane, and methyloctylsiloxane, a fluid copolymer of dimethylsiloxane, methyl(2-phenylpropyl)siloxane, a fluid copolymer of dimethylsiloxane and diphenylsiloxane, a fluid copolymer of dimethylsiloxane and methylvinylsiloxane, a fluid copolymer of dimethylsiloxane and methylphenylsiloxane, and a polydimethylsiloxane fluid having both molecular ends capped with trimethylsiloxy groups. The viscosity of component (G) at 25xc2x0 C. is in the range of from 10 mPaxc2x7s to 10,000 mPaxc2x7s, and preferably in the range of from 50 mPaxc2x7s to 5,000 mPaxc2x7s. The amount of component (G) is 1 part by weight to 50 parts by weight, preferably 5 parts by weight to 40 parts by weight per 100 parts by weight of component (A).
Furthermore, various additives and fillers normally added to coating materials can be appropriately added to the present composition. Specifically suggested are titanium oxide, ultramarine blue, Prussian blue, zinc white, rouge, chrome yellow, lead white, carbon black, transparent iron oxide, aluminum powder, and other inorganic pigments; azo pigments, triphenylmethane pigments, quinoline pigments, anthraquinone pigments, phthalocyanine pigments, and other organic pigments; rust preventives, UV absorbers, photostabilizers, anti-sagging agents, leveling agents, and other additives; quartz micropowder, calcium micropowder, fumed titanium dioxide, diatomaceous earth, aluminum hydroxide, microparticulate alumina, magnesia, zinc oxide, zinc carbonate and fillers obtained by treating the surface of the above with silanes, silazanes, low-polymerized siloxanes, organic compounds, etc.; fluororesin micropowder and other resin powders.
As a method for preparing the present composition, a process is suggested in which the above-mentioned component (A) to component (F), or component (A) to component (G) are subjected to kneading using well-known kneading equipment, such as a Ross mixer, a Hobart mixer, a TORERO mixer, a roll mixer, a Henschel mixer, a Banbury mixer, a kneader-mixer, a flowjet mixer, a ball mill, a vibrating mill, a screw extruder, a paddle mixer, a ribbon mixer, and other kneading equipment. Also, in the process of mixing, the mixture may be heated, preferably to a temperature of 30 to 200xc2x0 C. Although kneading can be carried out in an any order, possible examples may include a process, in which component (A) to component (G) are kneaded simultaneously; a process in which a solution is prepared by kneading component (A), component (B), and component (D), and another solution is prepared by kneading component (C), component (E), component (F), and component (G), followed by mixing the two solutions; and a process, in which a solution is prepared by kneading component (A), component (B), component (D), and component (G), and another solution is prepared by kneading component (C), component (E), and component (F), followed by mixing the two solutions. The viscosity of the composition of the present invention at 25xc2x0 C. is typically in the range of from 1,000 mPaxc2x7s to 15,000 mPaxc2x7s. In addition, because the viscosity range fluctuates depending on the conditions, it is preferable to indicate the range by measuring it at 60 rpm using a V-type rotary viscometer (rotor No. 4).
Coating techniques which may be used with the present composition include, for example, dipping, spraying, brushing, and other techniques. After coating, the composition is normally allowed to cure at room temperature. Although the thickness of the coating film is not critical, it is preferable to use a thickness of 1 to 500 xcexcm.
The above-described water repellent silicone coating agent composition can be used as a water repellent coating agent for various metal substrates, mortar board, slate board, concrete, wood, plastic substrates, glass, and ceramic surfaces. It is particularly useful as a water repellent coating agent for pipelines, tanks, and other facilities located in the vicinity of a seashore.